1. Field of the Invention
The present invention relates to a vehicle cooling system, and more particularly, a system for separately cooling more than one vehicle space.
2. Background Art
There are a variety of vehicles today which utilize electricity, and in particular an electric motor, to at least assist in powering the vehicle. For example, there are electric vehicles, which are powered exclusively by an electric motor; hybrid electric vehicles (HEV), which may be selectively powered by an internal combustion engine or an electric motor; and fuel cell vehicles, or hybrid fuel cell vehicles, just to name a few. The electric motor used in such vehicles may have an electrical power source such as a fuel cell or a battery.
In the case of a battery used to provide power to an electric motor to drive a vehicle, the temperature of the battery can increase significantly when the motor is used for extended periods of time. The increase in battery temperature may be compounded when the battery is confined to a relatively small, enclosed space. If the increase in battery temperature is left unchecked, the battery life may be reduced. Thus, it is desirable to provide a system for cooling a battery, or batteries, in a vehicle to keep the battery temperature low enough that the battery life is not reduced.
In addition to the added requirement of keeping the battery cool in a hybrid electric vehicle, there is also a need to provide a cooling system for the vehicle passenger compartment, just as in a conventional vehicle. Although separate systems may be used to provide cool air to the battery and the vehicle passenger compartment, an integrated, or at least partially integrated, cooling system can be used. One attempt to provide an integrated cooling system for both a battery and a vehicle passenger compartment, is described in U.S. Pat. No. 6,138,466 issued to Lake et al. on Oct. 31, 2000.
Lake et al. discusses the use of a cooling system having an inside heat exchanger for adjusting the temperature of air flowing into the passenger compartment, and a zone-control heat exchanger which may be used for cooling a battery assembly. Lake et al. does not describe a mechanism for detecting the temperature of the air at each heat exchanger, and automatically stopping the flow of cooling fluid to a heat exchanger when the detected temperature falls below a predetermined temperature. Lake et al. does describe disabling operation of the inside heat exchanger when the ambient air temperature outside the vehicle is low, but this does not account for local temperatures near the heat exchanger, nor does it protect the zone-control heat exchanger from icing. In addition, Lake et al. does not describe a mechanism for providing fresh air directly across the battery. This may lead to unnecessary energy consumption, when the temperature of the ambient air outside the vehicle is low enough to cool the battery without the use of a heat exchanger.
Thus, a need still exists for a vehicle cooling system that at least partially integrates passenger compartment cooling and vehicle battery cooling, and includes a mechanism for automatically shutting off the flow of coolant to an individual heat exchanger when the temperature of that heat exchanger becomes too low, thereby helping to prevent icing on the heat exchanger. In addition, there exists a need for a vehicle cooling system that at least partially integrates passenger compartment cooling and vehicle battery cooling, and provides a fresh air intake directly connected to the vehicle battery, so that at least a portion of the vehicle cooling system can be shut down when the temperature of the ambient air outside the vehicle is low enough to adequately cool the battery without the use of the cooling system.